Sixty-years ago this month, a live biological payload consisting of a primate and a colony of mice was lofted to an altitude of 236,000 feet by a two-stage Aerobee X-8 sounding rocket. The mission marked the first recorded instance where a mamallian payload survived the rigors of high altitude rocket flight.
The post-World War II period saw a rapid expansion in America’s efforts to explore space. Emphasis was placed on flying faster and higher. Rocket power led the way. First, into the upper atmosphere, and ultimately into the lower reaches of space.
Early post-war flight research capitalized on using V-2 rockets captured from the defeated Third Reich. These vehicles were brought to America and adapted to boost instruments to high altitude. While servicable in this new role, the V-2 was less than ideal from the standpoints of launch, performance and payload recovery.
In light of the above, a variety of purpose-built rocket systems rapidly came into being during the post-war years. Prominent among these was the Aerobee high altitude sounding rocket. Aerojet General initiated development of the system in 1946. The first Aerobee test vehicle was flown in November of 1947 at White Sands proving Grounds (WSPG).
The first Aerobee configuration was about known as the X-8. It consisted of a solid propellant booster and a liquid sustainer. The booster generated 18,000 lbs of thrust for 2.5 seconds. Sustainer propellants included aniline and furfuryl-alcohol (fuel) and red fuming nitric acid (oxidizer). The sustainer rocket engine produced 2,600 lbs of thrust for 40 seconds.
The X-8 launch vehicle measured 26.4-feet in the length with a launch weight of about 1,100 lbs (including 150-lb payload). The sustainer stage was a little more than 20-feet in length and 15-inches in diameter. The launch weight of the booster was roughly 50 lbs more than that of the sustainer.
The X-8 was launched from a 143-foot tower which was typically canted 3-degrees off of the vertical. Booster burnout occurred at 950 ft/sec and 1,000 feet above the ground. Sustainer burnout took place at 4,420 ft/sec and an altitude of 17-nm. Apogee was on the order of 66-nm.
The Aerobee carried a variety of scientific instruments to probe the atmospheric and space environments. Measurements were made of high altitude thermodynamic properties, winds, radiation and magnetic fields. The Aerobee Program also provided a wealth of information regarding vehicle aerodynamics, flight dynamics and dispersion.
The Aerobee was also used to loft live biological payloads into near space. At the time this flight research began in the late 1940’s/early 1950’s, very little was known about the effects of high altitude rocket flight on living organisms. A variety of small animals were used as test subjects including primates, mice, and insects. The data obtained from these animal flights were ultimately used to safely launch men into space.
History records that it was not all that easy to rocket animals into space and have them survive the experience. Animals died either due to the rigors of rocket flight, launch vehicle failure or recovery system malfunction. Sometimes everything worked, but an animal died due to heat exhaustion when recovery crews could not extract it from the downed payload section soon enough. It would take over 3-years of flight experience before success was achieved.
The great day came on Thursday, 20 September 1951. An Aerobee X-8 RTV-A1 served as the launch platform. The live biological payload consisted of a monkey named Yorick and a colony of eleven (11) mice. The launch took place at 15:31 UTC from Holloman Air Force Base, New Mexico. The X-8 carried the monkey and mice payload to an apogee of 236,000 feet. The parachute recovery system finally worked. Recovery was also successful.
Many more successful Aerobee animal flights took place in the ensuing years. Even as Aerobee rocket performance increased significantly as numerous variants of the X-8 were developed over the life of the program. Indeed, almost 1,100 payloads were lofted into the realms above by the time the Aerobee was taken out of active service in 1985.
Fifty-two years ago this week, the United States Air Force successfully conducted an Initial Operational Capability Demonstration (IOC DEMO) of the Atlas D Intercontinental Ballistic Missile (ICBM). The Atlas Missile System was pronounced operational following the successful launch from Vandenberg Air Force Base, California.
Named for the superhuman strongman of Greek mythology, Atlas was the United States’ first operationally deployed intercontinental ballistic missile (ICBM). Program roots go back to 1946 when Consolidated Vultee Aircraft (Convair) was awarded a study contract by the United States Army Air Forces for a 1,500 to 5,000 mile range missile that could carry a nuclear warhead.
At the time Convair began its study, no missile within conception could carry even the smallest nuclear warhead available at the time. However, a confluence of technological developments in the early 1950’s led to Atlas becoming a high priority development within the United States defense community. First, the thermonuclear weapon was successfully demonstrated. Second, a design breakthrough occurred wherein nuclear warhead mass was sharply reduced. Finally, CIA activities revealed that the Soviet Union was making significant progress with their own ICBM program.
Atlas A, B and C were the initial test and development variants of America’s first ICBM. Atlas D was the first operational version. Configured with a Mark 2 reentry vehicle, it measured 75 feet in length and 10 feet in diameter. Atlas D weighed 255,000 lbs at launch and had a range of 10,360 miles.
The Atlas propulsion system consisted of a single Rocketdyne LR105 sustainer (57,000 lbs thrust) and a pair of Rocketdyne LR89 boosters (150,000 lbs thrust each). Roll control and fine velocity control was provided by a pair of Rocketdyne LR101 vernier rocket engines (1,000 lbs thrust each).
The Atlas sustainer rocket engine was mounted between the outboard booster rocket engines. This trio of rocket engines was ignited at launch. While the boosters were jettisoned around 130 seconds into flight, the sustainer core continued to fire until propellant exhaustion. This unique arrangement made Atlas a stage-and-a-half launch vehicle.
In striving for the minimum weight solution, the Atlas airframe included propellant tankage constructed of very thin stainless steel. This so-called “balloon tank” design required internal pressurization with nitrogen gas at about 5 psig to provide structural rigidity. An Atlas launch vehicle would simply collapse under its own weight if not so pressurized.
Atlas A, B, C and D variants employed radio guidance. That is, the missile sent position information from its guidance system to the ground via radio. In turn, the ground sent course correction information back to the missile. Starting with the Atlas E, the guidance system was entirely autonomous.
On Wednesday, 09 September 1959, the Strategic Air Command (SAC) conducted an Initial Operational Capability Demonstration (IOC DEMO) launch at Vandenberg Air Force Base, California. The Atlas D 12D launch vehicle lifted-off from Launch Complex 576-A2 at 17:50 UTC. Its Mark II reentry vehicle flew 4,480 nautical miles downrange and landed less than 1 nautical mile from its target near Wake Island. Apogee and maximum speed were 972 nautical miles and 16,000 mph, respectively.
The Atlas IOC DEMO mission was entirely successful. General Thomas D. Power, SAC Commander-in-Chief, was so impressed with the results of the flight that he immediately declared the Atlas System to be operational.
The Atlas missile ultimately stood sentinel at 11 separate launch sites located throughout the United States. Roughly 350 Atlas missiles were manufactured during the program’s lifetime, with a maximum of 129 missiles being deployed at any one time being 129. However, the introduction of the famous Minuteman missile in 1963 sounded the death knell for Atlas. Indeed, there were no more operational Atlas missiles after April of 1965.
Although its operational service life was somewhat brief, Atlas provided a proving ground for a multiplicity of emerging missile technologies. Further, Atlas development served as the organizational and procedural template for all future ICBM programs.
Following retirement from active ICBM service, depostured Atlas ICBM’s were converted to the space launch role. It was employed for nearly a quarter of a century in such capacity. Indeed, all Mercury Earth-orbital missions were launched using man-rated Atlas launch vehicles.
The Atlas is still active in the US launch vehicle inventory. Although now manufactured by Lockeed-Martin and having a configuration quite distinct from that of its ICBM forbears, the latest version of the venerable vehicle is the Atlas V. This modern Atlas variant can send nearly 65,000 lbs of payload into LEO and 29,000 lbs into GTO.
Fifty-five years ago this week, the USAF/Boeing KC-135A Stratotanker took to the skies for the first time. The jet-powered aircraft would go on to become the most famous military tanker in the history of aviation.
The KC-135A Stratotanker was a derivative of the famous Boeing Model 367-80. The type was the only jet-powered aircraft designed specifically for the aerial refueling mission. As such, it replaced the older and slower propeller-driven KC-97 Stratotanker. For the first 15 years of its operational life, the KC-135 was the only tanker flown by the Strategic Air Comman (SAC).
The KC-135A measured 136.25 feet in length and had a wingspan of 130.8 feet. Gross take-off weight and empty weight were 297,000 lbs and 109,000 lbs, respectively. Four (4) wing pylon-mounted Pratt and Whitney J57-P-59W turbojets provided a sea level thrust of 58,000 lbs in afterburner. The aircraft was designed to have an unrefueled range of 4,000 miles, a cruise speed of 552 mph and an operational ceiling of 40,000 feet.
Jet fuel was carried internally within six (6) wing tanks and four (4) fuselage tanks. All but 1,000 gallons of this fuel could be pumped to the receiver aircraft via an extendable boom located at the rear of the tanker. The KC-135 boom operator would lie in a prone position and actually flew the boom into the receiving aircraft’s fuel receptacle.
On Friday, 31 August 1956, the first KC-135A Stratotanker production aircraft made its maiden flight from the Boeing airfield at Renton, Washington. Known as the “The City of Renton”, this aircraft was the first of 820 KC-135 aircraft that Boeing would ultimately produce. Roughly 90 percent of these production aircraft were true tankers while the remainder were employed as cargo transports and flying command posts.
The service that the KC-135 has provided to our nation’s aerial warfighters has truly been astounding. For example, during nine years of the Vietnam conflict, KC-135s made 813,000 aerial refuelings of combat aircraft. In support of the Persian Gulf conflict, KC-135 tankers made 18,700 hookups and transferred 278,000,000 lbs of fuel.
The KC-135 has evolved into numerous variants over the course of its long operational life. A variety of modifications have extended the service life of the KC-135 into its sixth decade. Key upgrades include reskinning the wings with an improved aluminum alloy and more powerful and fuel-efficient CFM-56 turbofans. Total sea level thrust is more than 90,000 lbs in afterburner.
As a tribute to this venerable aircraft, her designers and her flight crews, we note here that the KC-135 Stratotanker remains the primary USAF aerial refueling aircraft to this very day.
Fifty-seven years ago this month, USAF Major Arthur W. “Kit” Murray set a new world altitude record of 90,440 feet in the rocket-powered Bell X-1A. In doing so, Murray reported that he could detect the curvature of the Earth from the apex of his trajectory.
The USAF/Bell X-1A was designed to explore flight beyond Mach 2. The craft measured 35.5 feet in length and had a wing span of 28 feet. Gross take-off weight was 16,500 pounds. Power was provided by an XLR-11 rocket motor which produced a maximum sea level thrust of 6,000 lbs. This powerplant burned 9,200 pounds of propellants (alcohol and liquid oxygen) in about 270 seconds of operation.
Similar to other early rocket-powered X-aircraft such as the Bell XS-1, Douglas D-558-II, Bell X-2 and North American X-15, the X-1A flew two basic types of high performance missions. That is, the bulk of the vehicle’s propulsive energy was directed either in the horizontal or in the vertical. The former was known as the speed mission while the latter was called the altitude mission.
On Saturday, 12 December 1953, USAF Major Charles E. “Chuck” Yeager flew the X-1A (S/N 48-1384) to an unofficial speed record of 1,650 mph (Mach 2.44). Moments after doing so, the X-1A went divergent in all three axes. The aircraft tumbled and gyrated through the sky. Control inputs had no effect. Yeager was in serious trouble. He could not control his aircraft and punching-out was not an option. The X-1A had no ejection seat.
Chuck Yeager took a tremendous physical and emotional beating for more than 70 seconds as the X-1A wildly tumbled. His helmet hit the canopy and cracked it. He struck the control column so hard that it was physically bent. His frantic air-to-ground communications were distinctly those of a man who was convinced that he was about to die.
As the X-1A tumbled, it decelerated and lost altitude. At 33,000 feet, a battered and groggy Yeager found himself in an inverted spin. The aircraft suddenly fell into a normal spin from which Yeager recovered at 25,000 feet over the Tehachapi Mountains situated northwest of Edwards. Somehow, Yeager managed to get himself and the X-1A back home intact.
The culprit in Yeager’s wide ride was the then little-known phenomenon identified as roll inertial coupling. That is, inertial moments produced by gyroscopic and centripetal accelerations overwhelmed aerodynamic control moments and thus caused the aircraft to depart controlled flight. Roll rate was the critical mechanism since it coupled pitch and yaw motion.
In the aftermath of Yeager’s near-death experience in the X-1A, the Air Force ceased flying speed missions with the aircraft. Instead, a series of flights followed in which the goal was to extract maximum altitude performance from the aircraft. USAF Major Arthur W. “Kit” Murray was assigned as the Project Pilot for these missions.
On Thursday, 26 August 1954, Kit Murray took the X-1A (S/N 48-1384) to a maximum altitude of 90,440 feet. This was new FAI record. Murray also ran into the same roll inertial coupling phenomena as Yeager. However, his experience was less tramatic than was Yeager’s. This was partly due to the fact that Murray had the benefit of learning from Yeager’s flight. This allowed him to both anticipate and know how to correct for this flight disturbance.
Murray’s achievement in the X-1A meant that the X-1A held the records for both maximum speed and altitude for manned aircraft. It did so until both records were eclipsed by the Bell X-2 in September of 1956.
Kit Murray was a highly accomplished test pilot who never received the public adulation and notoreity that Chuck Yeager did. He retired from the Air Force in 1960 after serving for 20 years in the military. Murray went on to a very successful career in engineering following his military service. Kit Murray lived to the age of 92 and passed from this earthly scene on Monday, 25 July 2011.
Fifty-four years ago this week, USAF Major David G. Simons, MD successfully completed the Manhigh II high-altitude balloon mission. Simons’ epic flight lasted 32 hours and established an altitude record of 101,516 feet.
Project Manhigh was a United States Air Force biomedical research program that investigated the human factors of spaceflight by taking men into a near-space environment. Preparations for the trio of Manhigh flights began in 1955. The experience and data gleaned from Manhigh were instrumental to the success of the nation’s early manned spaceflight effort.
The Manhigh target altitude was approximately 100,000 feet above sea level. A helium-filled polyethylene balloon, just 0.0015-inches thick and inflatable to a maximum volume of over 3-million cubic feet, carried the Manhigh gondola into the stratosphere. At float altitude, this balloon expanded to a diameter of about 200 feet.
The Manhigh gondola was a hemispherically-capped cylinder that measured 3-feet in diameter and 8-feet in length. It was attached to the transporting balloon via a 40-foot diameter recovery parachute. Although compact, the gondola was amply provisioned with the necessities of flight including life support, power and communication systems. It also included expendable ballast for use in controlling the altitude of the Manhigh balloon.
The Manhigh test pilot wore a T-1 partial pressure suit during the Manhigh mission. This would protect him in the event that the gondola cabin lost pressure at extreme altitude. The pilot was hooked-up to a variety of sensors which transmitted his biomedical information to the ground throughout the flight. This allowed medicos on the ground to keep a constant tab on the pilot’s physical status.
The flight of Manhigh I took place on Sunday, 02 June 1957 with USAF Captain Joseph W. Kittinger as pilot. Kittinger reached an altitude of 95,200 feet. Though successful in the main, the mission was cut short due to rapid depletion of the oxygen supply. This was caused by accidental crossing of the oxygen supply and vent lines prior to flight. Total mission time was 6 hours and 32 minutes.
Manhigh II was launched at 1422 UTC from Portmouth Mine in Crosby, Minnesota on Sunday, 18 August 1957. USAF Major David G. Simons, a medical doctor, flew this nominally 24-hour mission. Simons uneventful ascent to Flight Level 1,000 took 2 hours and 18 minutes. A maximum altitude of 101,516 feet was ultimately recorded during Manhigh II.
Simons’ flight was taxing both physically and mentally. Cabin environmental management issues and the frequent need to monitor and control atitude so as to remain sufficiently above thunderstorm activity were the primary stressors. However, the pilot dutifully went about conducting a variety of more than 25 different scientific experiments. Simon’s flight came to a successful conclusion when his gondola landed in an alfalfa field near Frederick, South Dakota at 22:32 UTC on Monday, 19 August 1957.
By way of postscript, Manhigh III was successfully conducted on Wednesday, 08 October 1958. Launch occurred at Holloman AFB, New Mexico with USAF Lt Clifton M. McClure as pilot. The mission’s success was largely due to McClure’s super-human efforts in overcoming a variety of life-threatening problems. However, that story will be reserved for another day.
The contributions made to aero medical science by the Manhigh Program were significant. Indeed, information gleaned from this flight research effort tangibly influenced future manned flight including the X-15 Program, Project Excelsior and Project Mercury. To get a fuller appreciation for Manhigh’s significance in aerospace history, the interested reader is invited to read Simons 1962 book aptly entitled “Manhigh”.
David Simons continued to serve his country as an officer in the United States Air Force for another 8 years following his Manhigh II flight. He retired from the junior service in 1965 as a Lieutenant Colonel. In civilian life, he went on to become an internationally-recognized expert in the treatment of chronic pain. In April of 2010, Simons left this frail existence while in his 88th year.
Fifty-one years ago this month, an United States Air Force C-119 Flying Boxcar aircraft successfully performed the first mid-air retrieval of a reentry body as it was returning from space. The recovered vehicle was named Discoverer XIV.
Corona was a covert reconnaissance program operated by the United States government from June of 1959 to May of 1972. The national security mission was to photographically surveil denied territory from orbit. The exposed film was then returned to Earth via a reentry capsule and recovered for subsequent development and photogrammetric analysis.
An evolutionary series of satellites, code named Key Hole (KH), were flown during the Corona Program. A total of 144 satellites were flown over the course of the surveillance effort; 71% of which provided useful results. Although not addressed here, the history of the development of the Key Hole camera system is a fascinating story in its own right.
A Corona satellite orbited the Earth at altitudes between 89 and 250 nautical miles. From its perch high in the heavens, the orbiting eye-in-the-sky exposed almost 6 statute miles of film during a typical mission. The camera systems used early in the Corona Program provided a target resolution of 25 feet. Later systems delivered a resolution of 6 feet.
The Discoverer Program served as a public front for Corona. Labled as a space technology development program, Discoverer was in fact used to fly the early Key Hole camera systems. The satellite also served as the means to develop and refine mid-air retrieval techniques for recovery of the Corona film canister. The last Discoverer mission (Discoverer XXXIX) was flown in April of 1962.
Successful recovery of the Corona film canister from orbit required precise targeting of the reentry vehicle. This would put the recovery aircraft in a position to make a mid-air retrieval. A special line suspension system deployed under the aircraft was used to snag the reentry vehicle as it slowly decended on its parachute. Once retrieved in this manner, the entire assemblage was reeled into the back of the recovery aircraft.
Success did not come easy for the Discoverer Program. The first dozen missions were failures for one reason or another. Either the satellite failed to achieve orbit or the recovery operation was unsuccessful. However, the importance of the mission was such that development flights continued.
Successful recovery of a Discoverer reentry capsule finally came on Thursday, 11 August 1960. Discoverer XIII had been boosted into a polar orbit by a Thor-Agena launch vehicle the previous day and had orbited the Earth 17 times before its return from space. Despite excellent placement into the target area, successful mid-air retrieval of the reentry vehicle did not occur. Navy frogmen had to fish Discoverer XIII out of the water.
Discoverer XIV was launched into space by a Thor-Agena launch vehicle on Thursday, 18 August 1960. After 17 polar orbits, the reentry vehicle returned to Earth on Friday, 19 August 1960. The mission was very successful including the mid-air retrieval operation. Interestingly, it wasn’t until the 3rd pass that the C-119 Flying Box Car from the 6593rd Test Squadron at Hickam AFB, Hawaii successfully made the grab. Nevertheless, Discoverer XIV became the first reentry vehicle in history to be recovered via mid-air retrieval.
The Corona Program went on to a highly successful operational life. The information gathered therein provided a tangible check on communist military activity and measurably improved the security of not only the United States, but that of the entire free world. Indeed, Corona was a key part of the national security apparatus at a time when the nuclear damocles hung in a particularly menacing manner over the heads of all those who hallow freedom.
Fifty-seven years ago this week, the USN/Convair YF2Y-1 Sea Dart became the first and only seaplane ever to exceed the speed of sound. Convair test pilot Charles E. Richbourg was at the controls of the experimental sea-based fighter.
In 1948, the United States was looking to develop a sea-based supersonic fighter as a means projecting naval airpower. However, few in the Navy at that time believed that such as aircraft could be operated successfully from an aircraft carrier. Thus, the new aircraft would need to be a seaplane That is, it would take-off and land in the ocean.
Consolidated Vultee Aircraft (Convair) won a competition for a Navy contract to build and flight test a pair of supersonic seaplane prototypes. Convair’s winning airframe featured a delta wing, a large triangular vertical tail, twin afterburning turbojets and dual retractable hydro-skis. Known as the XFY2-1 Sea Dart, the two protoype aircraft were assigned BuAer tail numbers 137634 and 137635, respectively.
The Sea Dart’s nominal specifications included a length of 52.5 ft, a wingspan of 33.7 ft and an empty weight of 12,625 lbs. The single-place aircraft was initially powered by twin Westinghouse J46-WE-2 turbojets. Each of these non-afterburning powerplants produced a meager 3,400 lbs of sea level thrust. This led to the aircraft being significantly underpowered.
The XF2Y-1 design maximum speed was 825 mph, a rate of climb of 17,000 ft/min and a service ceiling of nearly 55,000 ft. The type’s take-off speed from the water was approximately 145 mph. Although the prototypes were never outfitted with armament, an operational Sea Dart reportdely would have had a mix of 4 x 20mm cannon, a bevy of 2.75-inch unguided rockets and a pair of air-to-air missiles.
Convair test pilot Ellis D. Shannon made the official first flight of XF2Y-1 Ship No. 1 (BuAer 137634) on Thursday, 09 April 1953. San Diego Bay served as the take-off and landing site. Shannon quickly determined that the XF2Y-1 was indeed underpowered. The aircraft’s hydro-skis also vibrated badly during ocean take-off and landing. The result was that the XF2Y-1 was quite challenging to control during high-speed ocean surface operations.
The second Sea Dart to fly was the first YF2Y-1 (BuAer 135762)aircraft. The main difference between the YF2Y-1 and XF2Y-1 was the propulsion system. Specifically, the YF2Y-1 was powered by afterburning J46 turbojets and its air induction and exhaust systems were configured differently. With the introduction of the YF2Y-1, the XF2Y-1 was cancelled by the Navy.
Flight testing of the YF2Y-1 Sea Dart began in early 1954. Convair test pilot Charles E. Richbourg was assigned to make the initial flights in Ship No. 1. The zenith of the YF2Y-1’s flight test program occurred on Tuesday, 03 August 1954 when Richbourg flew the seaplane faster than the speed of sound while passing through 34,000 feet in a shallow dive. This event marked the first and only time in aviation history that a seaplane exceeded Mach 1.
The Sea Dart’s bright moment of achievement was followed several months later by the program’s darkest day. On Thursday, 04 November 1954, Richbourg was performing a XF2Y-1 flight demonstration for Navy leadership and members of the press over San Diego Bay when structural failure of the aircraft’s left wing caused it to distintegrate in flight. Rescue forces quickly found Richbourg and pulled him out of the water. However, the 31 year-old pilot did not survive.
The loss of the first YF2Y-1 came at a time when the Navy was already losing interest in the Sea Dart Program. The service had rethought the notion of operating a high-performance aircraft from its carrier force and now reckoned that such operations were indeed possible. These realities, coupled with the Sea Dart’s seemingly unsolvable hydro-ski vibration problems, effectively sounded the death knell of Convair’s supersonic seaplane concept.
Notwithstanding the above, it would not be until the fall of 1957 that the Sea Dart Program would officially come to an end. Actually, three (3) more YF2Y-1 airframes were manufactured. Sea Dart Ship No. 3 (BuAer 13563) flew for the first time on Friday, 04 March 1955. This aircraft was used mainly for flight testing various hydro-ski arrangements. Sea Dart Ship No. 4 (BuAer 135764) and Ship No. 5 (BuAer 135765) never flew.
Sixty-one years ago this month, the United States Army’s Bumper-WAC No. 7 two-stage rocket reached a maximum speed of 8,213 ft/sec (Mach 9). This concluding flight of the Bumper Program was flown from the Long-Range Proving Ground (LRPG) in Florida.
The Bumper Program was a United States Army effort to reach flight altitudes and velocities never before achieved by a rocket vehicle. The name “Bumper” was derived from the fact that the lower stage would act to “bump” the upper stage to higher altitude and velocity than it (i.e., the upper stage) was able to achieve on its own.
The Bumper Program, which was actually part of the Army’s Project Hermes, officially began on Friday, 20 June 1947. The project team consisted of the General Electric Company, Douglas Aircraft Company and Cal Tech’s Jet Propulsion Laboratory. A total of eight (8) test flights took place between May 1948 and July 1950.
The Bumper two-stage configuration consisted of a V-2 booster and a WAC Corporal upper stage. The V-2′s had been captured from Germany following World War II while the WAC Corporal was a single stage American sounding rocket. The launch stack measured 62 feet in length and weighed around 28,000 pounds.
Propulsion-wise, the V-2 booster generated 60,000 pounds of thrust with a burn time of 70 seconds. The WAC Corporal rocket motor produced 1,500 pounds of thrust and had a burn time of 47 seconds.
The flight of Bumper-WAC No. 1 occurred on Thursday, 13 May 1948. This was an engineering test flight in which the WAC Corporal achieved a peak altitude of 79 miles. Unfortunately, the next three (3) flights were plagued by development problems of one kind or another and failed to achieve an altitude of even 10 miles.
Bumper-WAC No. 5 was fired from WSPG on Thursday, 24 February 1949. The V-2 burned-out at an altitude of 63 miles and a velocity of 3,850 feet per second. The WAC Corporal accelerated to a maximum velocity of 7,550 feet per second and then coasted to an apogee of 250 miles. With generation of a very thin bow shock layer and high aerodynamic surface heating levels, this flight can be considered as the first time a man-made flight vehicle entered the realm of hypersonic flight.
Three (3) more Bumper-WAC missions would follow Bumper-WAC No.5. While Bumper-WAC No. 6 would fly from WSPG, the final two (2) missions were conducted from an isolated Florida launch site in July of 1950. The hot, bug-infested Floridian launch location, springing-up amongst sand dunes and scrub palmetto, would one day become the seat of American spaceflight. It was known then as the Long-Range Proving Ground (LRPG). Today, we know it as Cape Canaveral.
Bumper-WAC No. 7 was supposed to be the first rocket fired from the LRPG. However, Bumper-WAC No. 8 got that honor when No. 7 experienced a glitch on the pad. No. 8 was fired at 13:29 UTC on Monday, 24 July 1950. The mission failed when the rocket motor of the WAC upper stage did not ignite.
On Saturday, 29 July 1950, Bumper-WAC No. 7 was launched from the LRPG. The resulting flight achieved the highest kinematic performance of the Bumper Program. The WAC upper stage burned-out at 8,213 ft/sec (Mach 9) and flew 150 miles downrange. The maximum velocity within the atmosphere was more than 3,200 mph – a record for the time.
The Bumper Program successfully demonstrated the efficacy of the multi-staging concept. Bumper also provided valuable flight experience in stage separation and high altitude rocket motor ignition systems. In short, Bumper played a vital role in helping America successfully develop its ICBM, satellite and manned spaceflight capabilities.
While its historical significance, and even its existence, has been lost to many here in the 21st Century, the Bumper Program played a major role in our quest for the Moon. As such, it will forever hold a hollowed place in the annals of United States aerospace history.
Fifty-years ago this week, Mercury Seven Astronaut Vigil I. “Gus” Grissom, Jr. became the second American to go into space. Grissom’s suborbital mission was flown aboard a Mercury space capsule that he named Liberty Bell 7.
The United States first manned space mission was flown on Friday, 05 May 1961. On that day, NASA Astronaut Alan B. Shepard, Jr. flew a 15-minute suborbital mission down the Eastern Test Range in his Freedom 7 Mercury spacecraft. Known as Mercury-Redstone 3, Shepard’s mission was entirely successful and served to ignite the American public’s interest in manned spaceflight.
Shepard was boosted into space via a single stage Redstone rocket. This vehicle was originally designed as an Intermediate-Range ballistic Missile (IRBM) by the United States Army. It was man-rated (that is, made safer and more reliable) by NASA for the Mercury suborbital mission. A descendant of the German V-2 missile, the Redstone produced 78,000 lbs of sea level thrust.
Shepard’s suborbital trajectory resulted in an apogee of 101 nautical miles (nm). With a burnout velocity of 7,541 ft/sec, Freedom 7 splashed-down in the Atlantic Ocean 263 nm downrange of its LC-5 launch site at Cape Canaveral, Florida. Shepard endured a maximum deceleration of 11 g’s during the reentry phase of the flight.
Mercury-Redstone 4 was intended as a second and confirming test of the Mercury spacecraft’s space-worthiness. If successful, this mission would clear the way for pursuit and achievement of the Mercury Program’s true goal which was Earth-orbital flight. All of this rested on the shoulders of Gus Grissom as he prepared to be blasted into space.
Grissom’s Liberty Bell 7 spacecraft was a better ship than Shepard’s steed from several standpoints. Liberty Bell 7 was configured with a large centerline window rather than the two small viewing ports featured on Freedom 7. The vehicle’s manual flight controls included a new rate stabilization system. Grissom’s spacecraft also incorporated a new explosive hatch that made for easier release of this key piece of hardware.
Mercury-Redstone 4 (MR-4) was launched from LC-5 at Cape Canaveral on Friday, 21 July 1961. Lift-off time was 12:20:36 UTC. From a trajectory standpoint, Grissom’s flight was virtually the same as Shepard’s. He found the manual 3-axis flight controls to be rather sluggish. Spacecraft control was much improved when the new rate stabilization system was switched-on. The time for retro-fire came quickly. Grissom invoked the retro-fire sequence and Liberty Bell 7 headed back to Earth.
Liberty Bell 7’s reentry into the Earth’s atmosphere was conducted in a successful manner. The drogue came out at 21,000 feet to stabilize the spacecraft. Main parachute deployed occurred at 12,300 feet. With a touchdown velocity of 28 ft/sec, Grissom’s spacecraft splashed-down in the Atlantic Ocean 15 minutes and 32 seconds after lift-off. America now had both a second spaceman and a second successful space mission under its belt.
Following splashdown, Grissom logged final switch settings in the spacecraft, stowed equipment and prepared for recovery as several Marine helicopters hovered nearby. As he did so, the craft’s new explosive hatch suddenly blew for no apparent reason. Water started to fill the cockpit and the surprised astronaut exited the spacecraft as quickly as possible.
Grissom found himself outside his psacecraft and in the water. He was horrfied to see that Liberty Bell 7 was in imminent peril of sinking. The primary helicopter made a valiant effort to hoist the spacecraft out of the water, but the load was too much for it. Faced with losing his vehicle and crew, the pilot elected to release Liberty Bell 7 and abandon it to a watery grave.
Meanwhile, Grissom struggled just to stay afloat in the churning ocean. The prop blast from the recovery helicopters made the going even tougher. Finally, Grissom was able to retrieve and get himself into a recovery sling provided by one of the helicopters. He was hoisted aboard and subsequently delivered safely to the USS Randolph.
In the aftermath of Mercury-Redstone 4, accusations swirled around Grissom that he had either intentionally or accidently hit the detonation plunger that activated the explosive hatch. Always the experts on everything, especially those things they have little comprehension of, the denizens of the press insinuated that Grissom must have panicked. Grissom steadfastly asserted to the day that he passed from this earthly scene that he did no such thing.
Liberty Bell 7 rested at a depth of 15,000 feet below the surface of the Atlantic Ocean until it was recovered by a private enterprise on Tuesday, 20 July 1999; a day short of the 38th anniversary of Gus Grissom’s MR-4 flight. The beneficiary of a major restoration effort, Liberty Bell 7 is now on display at the Kansas Cosmosphere and Space Center. The spacecraft’s explosive hatch was never found.
As for Gus Grissom, ultimate vindication of his character and competence came in the form of his being named by NASA as Commander for the first flights of Gemini and Apollo. Indeed, Grissom and rookie astronaut John W. Young successfully made the first manned Gemini flight in March of 1965 during Gemini-Titan 3. Later, Grissom, Edward H. White II and Roger B. Chaffee trained as the crew of Apollo 1 which was slated to fly in early 1967. History records that their lives were cut short in the tragic and infamous Apollo 1 Spacecraft Fire of Friday, 27 January 1967.
Fifty-six years ago this month, the USAF/Republic XF-84H experimental turboprop fighter took to the air for the first time. The test hop originated from and recovered at Edwards Air Force Base, California.
The turbojet-powered XF-84H was a variant of Republic Aviation’s F-84 Thunderstreak. An Allison XT40-A-1 turboprop engine, rated at 5,850 hp, served as the power source for this novel aircraft. The XT40 drove a variable-pitch, 3-blade, 12-foot diameter propeller at 3,000 rpm. Thrust level was changed by varying blade pitch.
Owing to its high rotational speed and large diameter, the outer 2 feet of the XF-84H propeller saw supersonic velocities. The shock waves that emanated from the prop produced a deafening wall of sound. The extreme sound level produced intense nausea and raging headaches in ground crewmen. As a result, the XF-84H was dubbed the “Thunderscreech”.
The prop wash from the aircraft’s powerful turboprop necessitated the use of a T-tail to keep the horizontal tail and elevator in clean air flow. The engine’s extreme torque was partially countered by differential deflection on the left and right wing flaps and by placement of the left wing root air intake a foot ahead of the right intake.
A pair of XF-84H prototype aircraft (S/N 51-17059 and S/N 51-17060) was built by Republic Aviation. The first flight of an XF-84H took place on Friday, 22 July 1955 at Edwards Air Force. The flight was made by Republic test pilot Henry G. “Hank” Beaird, Jr. in Ship No. 1 (S/N 51-17059). The flight was cut short by a forced landing.
A total of twelve (12) test flights were made in the two Thunderscreech prototypes; eleven (11) in Ship No. 1 and one (1) in Ship No. 2. Total flight time accumulated by these experimental airframes was 6 hours and 40 minutes. The majority of flights experienced forced landings for one reason or another.
The XF-84H suffered from reduced longitudinal stability and poor handling qualities. The aircraft was also plagued by frequent engine, hydraulic system, nose gear and vibration problems. Faced with the type’s obvious non-viability, USAF opted to cancel the XF-84H Program in September of 1956.
Historical records indicate that the XF-84H reached a top speed of 520 mph during its brief flight test life. This figure was a full 120 mph short of the aircraft’s design speed. Nonetheless, the XF-84H held the speed record for single-engine prop-driven aircraft until Monday, 21 August 1989. On that date, a specially modified Grumman F8F Bearcat established the existing record of 528.33 mph.
